1. Field of Invention
The present invention relates to a unit circuit, an electronic circuit, an electro-optic apparatus, a driving method, and electronic equipment which can compensate for variations in the characteristics of transistors to drive current-type driven elements, such as organic electroluminescent elements.
2. Description of Related Art
Recently, organic EL (electroluminescent) elements have attracted attention as becoming the next-generation light-emitting devices to replace conventional LCD (Liquid-Crystal Display) elements. Organic EL elements have excellent characteristics when used in display panels, for example, they are subject to a smaller dependence on the viewing angle because they are self-luminous, and they consume less power because they do not need a backlight or reflected light.
Examples of a related art circuit to drive such an organic EL element include the configuration shown in FIG. 14. In this circuit, the drain of a driving transistor Tr1 is connected to a current-type driven element L (organic EL element) via a hole injection electrode. The gate of a switching transistor Tr3 is connected to a scanning line S, the source thereof is connected to a data line D, and the drain thereof is connected to the gate of the driving transistor Tr1 and one end of a capacitor element C. The other end of the capacitor element C is connected to a power-supply line V. The on/off state of the switching transistor Tr3 is controlled by a selection electrical potential supplied from the scanning line S to the gate, and electrical charge is stored in the capacitor element C by a signal voltage supplied from the data line D during the on period.
Then, a voltage across the terminals of the capacitor element C, which is due to this electrical charge, causes a voltage to be applied to the gate of the driving transistor Tr1, and an electrical current Ids corresponding to this voltage is supplied from the power-supply line V to the driven element L. The conductance between the source and the drain of the driving transistor Tr1 is controlled according to the voltage applied to the gate of the driving transistor Tr1, thus determining the luminance of the organic EL element, which is the driven element L.